~1 or 2/3 full days recommended
Sun Moon Lake is a beautiful lake with a stunning backdrop of mountains. Around the lake, there are numerous trails to walk, several temples to visit and cycle lanes.
How to get there: You can take a train to Nantou and take a bus from there but I think the easiest way (which I took) is to take a direct bus from Taipei (Taipei Main Station’s West bus station, Terminal B) to Sun Moon Lake with 國光客運 Kuo-Kuang buses. It costs around 400NTD and takes ~3 and half hours. The bus drops you in front of Shueishe Visitor Centre, from here, bike rentals and the docks are very close!
I recommend one day if you just want to cycle around the lake and take in some amazing sights, but two/three full days if you also want to explore and hike. Things around the lake are fairly cheap, you can get bikes & boat tickets for a whole day for about 100NTD. For the boat, they will give you a stamp on your hand which will allow you on numerous trips, be careful that your stamp doesn't fade! For bikes, they will ask you to leave an identity card of some kind but they do accept Taiwanese student cards as proof. Favourite places: Xuanzang temple & Ci-en Pagoda. Favourite bike route: from Delight Mall (Shueishe Visitor Centre) down to Xiangshan Visitor Centre. I didn't stay long here but I had such a great time cycling round!